Heat conductor

ABSTRACT

A heat conductor for floating on molten metal in a metal melting furnace to forestall the formation of metal oxide dross on the molten metal surface and for passing heat into the molten metal bath. The heat conductor may be partially hollowed out to enable it to float on the lighter molten metals and, in one form, comprises an open-top, boxlike structure having a floor formed of corrugations forming interior and exterior transfer fins. The heat conductor is preferably formed of silicon carbide which is an excellent heat transmitter and will not pass into or combine chemically with the molten metal to form an alloy or compound therewith.

United States Patent 72] Inventor Robert J. Sparks 7250 Brecksville Road, Independence, Ohio 44131 [211 App]. No. 838,553 [22] Filed July 2, 1969 [45] Patented Jan. 11, 1972 [54] HEAT CONDUCTOR 1 Claim, 8 Drawing Figs.

[52] U.S. Cl 165/185, 165/186, 263/5 l 266/1, 266/33 [5 l Int. Cl F28t 7/00, C2lb 1 1/00 [50] Field of Search l65/l 85, 186, 86; 62/461; 263/l l, 5 l; 266/33, 34

[56] References Cited UNITED STATES PATENTS 2,252,225 8/194! Bonsall 62/461 X 2,254,809 9/1941 Tharaldsen 263/42 2,738,l80 3/1956 Jerkas 266/33 X FOREIGN PATENTS 1,093,161 11/1960 Germany 266/33 Primary Examiner-William F. O'Dea Assistant Examiner-P. D. Ferguson Attorney-Baldwin, Egan, Walling & Fetzer ABSTRACT: A heat conductor for floating on molten metal in a metal melting furnace to forestall the formation of metal oxide dross on the molten metal surface and for passing heat into the molten metal bath. The heat conductor may be partially hollowed out to enable it to float on the lighter molten metals and, in one form, comprises an open-top, boxlike structure having a floor formed of corrugations forming interior and exterior transfer fins. The heat conductor is preferably formed of silicon carbide which is an excellent heat transmitter and will not pass into or combine chemically with the molten metal to form an alloy or compound therewith.

QIS

I \l/ |2v z z j 1 .1111" 1 1/ l I, 5 o -l8 I PAIENIEII m1 1 1972 3,833,866

SHEET 1 0F 2 FIG.2

INVENTOR. ROBERT J. SPARKS ATTORNEYS PATENTEDJMHHHYZ 3.633.666

SHEET 2 OF 2 INVENTOK ROBERT J. SPARKS ATTORNEYS HEAT CONDUCTOR This invention relates to indirect heating of molten metal and more particularly to heat conductors for floating on molten metal.

It is known that molten metals are generally poor absorbers of heat because of their reflectivity. In short, the metallurgical industry has been long handicapped in attaining desirable rates of heat transfer from radiant or reflective bodies to underlying pools of molten metal. Additionally, there is a tendency in many cases for a coating of metal oxide dross to accumulate on the surface of the molten metal, such oxide coating or film interfering with the rate of heat absorption and contributing to metal loss.

An important object of this invention is to improve the rate of heat transmission from a reflective furnace ceiling or overhead heat source to an underlying pool of molten metal.

A further object is to prevent the accumulation of metal oxide on the surface of molten metal receiving heat from a heat source or a reflective heating structure disposed thereabove.

A further object of the invention is to provide a heat conductor for floating on molten metal that will not contaminate or combine chemically with the molten metal to form an alloy or compound therewith.

Another object of the invention with respect to its use in an aluminum melting reverberation furnace is in increasing the rate of heat transfer from the radiant heating section of the furnace through the conductors to the molten metal bath.

A further object of the invention is to provide a heat conductor for floating on molten metal that is simple in construction, inexpensive to manufacture, and highly effective in operation.

Briefly, the foregoing objects are accomplished by the provision of a heat conductor for floating on molten metal or other liquid and preferably formed of silicon carbide. In one form of the invention the heat conductor is configured with a hollowed-out portion to enable the conductor to float on liquids such as light molten metals. The conductor may be dish or bowl shaped. In another form, the heat conductor is of square, planar configuration such that if a number of such conductors are placed side by side on a molten metal surface, such surface will be entirely covered thereby preventing the formation of metal oxide dross on such surface. In still another form of the invention, the heat conductor is an open-top, boxlike float having heat-conducting, interior and exterior ribs or fins in the floor thereof.

Thus, the invention provides a highly efficient heat conductor for transmitting heat reflected from a metal furnace ceiling back into the molten metal or for transmitting heat to the molten metal from an overhead heat source. Such heat conductors prevent metal oxide dross from forming on the molten metal surface. Additionally, the silicon carbide heat conductors will not contaminate or pass into or combine chemically with the molten metal solution and may be used over and over again with subsequent melts.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the drawings wherein:

FIG. 1 is a side elevational sectional view of a conventional metal melting furnace and showing heat conductors of the invention floating on the molten metal therein;

FIG. 2 is an enlarged view taken along the line 2-2 of FIG.

FIG. 3 is an enlarged perspective view of one of the heat conductors shown in FIG. 1;

FIG. 4 is a perspective view of a modified form of heat conductor of the invention;

FIG. 5 is a side elevational view of an overhead reverberatory heat transfer metal melting furnace and showing a plurality of another modified form of heat conductors of the invention floating on the molten metal therein;

FIG. 6 is an enlarged view taken along the line 66 of FIG.

FIG. 7 is an enlarged perspective view of one of the heat conductors shown in FIG. 5; and

FIG. 8 is a view taken along the line 8-8 of FIG. 7.

Although the invention is shown and described herein with reference to its use in metal melting furnaces, it will be understood that it may be used in any type of heating or melting furnace and may be used for floating on any type of heatable liquid.

The terms and expressions which have been employed are used as terms of description, and not of limitation, and there is no intention, in the use of such tenns and expressions, of excluding any equivalents of the features shown or described, or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

Referring first to FIG. 1, there is shown a conventional metal melting furnace F including a floor l0, sidewalls 12 and 14, and a heat-reflective roof or ceiling 16, said furnace containing a melt of molten metal or metal bath 18. Floating on the top surface of the molten metal 18 are a plurality of heat conductors or plates 20 of the invention configured for floating on a liquid and shown in perspective in FIG. 3.

The conductor 20 is a flat, planar configured plate, preferably rectangular or square in horizontal section, and having a centrally disposed, partially hollowed out portion or depression 22 enabling such conductor to float on heavy or light liquids.

FIG. 4 illustrates a modified heat conductor in the form of an annular dishor bowl-shaped plate or float 24 having a hollowed-out portion 26.

FIGS. 5 and 6 show an aluminum reverberatory furnace 30 typical of the aluminum industry and containing a melt of molten aluminum 32. The furnace 30 includes a heating section 31 and an external charging well 33. The heating section has a removable cover 35. Thus, in the metallurgical operation involving an aluminum reverberatory melting furnace 30, metal to be melted is charged into an external well 33 and the radiant heat is introduced from above into the bath 32 in the main heating section 31 of the furnace. The heat is then conducted through the bath 32 to the well 33 to melt the metal being charged. It is known that molten metals reflect radiant heat, especially aluminum. Therefore, in the conventional aluminum reverberatory furnace operation, approximately percent of the heat introduced is not used. The heat conductors of the invention correct this deficiency. Floating on the top surface of the molten metal 32 are a plurality of modified heat conductors 34 of the invention and shown in detail in FIGS. 7 and 8.

The furnace 30 is adapted to receive radiant heat from above the molten metal bath 32 (with the cover 35 being removed).

The conductors 34 are of open-top, boxlike configuration having sidewalls 40, 41, 42 and 43 and a floor 44. The floor 44 contains top or interior heat-conducting corrugations or fins 46 and bottom or exterior heat-conducting corrugations or fins 48 so that maximum surface area is exposed to receive and conduct the radiant heat into the bath 32 thereby effecting a more efficient transfer of heat. In the preferred form, the conductors 34 are approximately 1 foot by 1 foot in transverse section.

It is known that silicon carbide approaches a black body for receiving radiant heat. Also silicon carbide is a good conductor of heat. Accordingly, the conductors 20, 24 and 34 of the invention are preferably formed of silicon carbide as such material, in addition to being an excellent heat transmitter, will not contaminate or combine chemically with the molten metal. Silicon carbide will, at 2,000 F., absorb percent of radiant heat available. Other material, such as graphite or coal, will oxidize and disintegrate.

It will be noted in FIGS. 1 and 5 that the heat conductors are disposed in side-by-side relation on the molten metal surface so that such surface is entirely covered thereby preventing the formation of the aforementioned metal oxide dross thereon.

Thus, there is provided a heat conductor 34"confi gured to float on molten metal or any other liquid heatablein a reverberatory furnace. The heat conductor is 'finned inside and out melting furnace comprising, a flat planar plate of heat-conducting material configured for floating on a liquid, said plate being an open-top box having a floor formed of elongated parallel corrugations forming heat transfer fins, said plate being formed of silicon carbide. 

1. A heat conductor for floating on molten metal in a metal melting furnace comprising, a flat planar plate of heatconducting material configured for floating on a liquid, said plate being an open-top box having a floor formed of elongated parallel corrugations forming heat transfer fins, said plate being formed of silicon carbide. 